Mechanics~~~~~~~~~

(a) Take moment at the point where the wheel touches the kerb,
50 x [(1+0.2-0.5] = W x [square-root(1^2-0.5^2)]
where W is the weight of the wheel

solve for W

(b) The mimium force occurs when the perpendicular distance of the force from the pivot is maximum. This occurs when F is inclined upward at 45 degreeswith the horizontal. The perpendicular distance = (1+0.2) m = 1.2 m

Thus, F(min) x 1.2 = W x [square-root(1^2-0.5^2)]
using the result of W obtained in (a), solve for F(min)